If you set up Two-Factor Authentication (2FA) to log in to the Health Mate app, you will be provided with a recovery code in case you can't use your phone to access your account (e.g. you lost your phone or you've recently changed your phone number).
The recovery code is displayed at the end of the 2FA setup. It is a unique code that must be stored in a safe place (e.g. not on your phone since you will need the code if you do not have access to your phone). You can also access the code at a later time from within the Health Mate app: Profile > ⚙️ (top right-hand corner) > Account & Security > Two-Factor Authentication > Account Recovery and tap Recovery Code.